SD Card: Format & File Structure

How to set up files on the Micro SD Card

• SD Card can be Fat16 or Fat32 formatted. Most SD cards come Fat32 formatted, so you don't need to do anything
• They can be up to 32gb
• 32gb in the format described below = approximately 100 hours of recording time, 200 x 30 minute files or 16 banks x 12 x 30 minute files.
• Files should be:
  • Mono
  • 16 Bit
  • 44.1 hz
  • Headerless Wav files
  • using the .raw suffix
• The module can read up to 16 folders in the top level directory of the SD card
• Subdirectories will be ignored, folders beyond 16 will be ignored
• Each folder becomes a bank on the module
• Banks are created in xx order [to come]
• Each folder can contain up to xx files. More files make it harder to accurately select the files with the knob or control voltage

Creating headerless .raw wav files in Audacity

• Open your source file - i.e. a stereo MP3
• Ensure Project Rate is set to 44100 (Bottom left hand corner of the screen)
• Mix to Mono (Tracks / Stereo Track to Mono)
• You may want to apply some audio compression to even out levels
• You can remove any silence from the sample using Effect / Truncate Silence
• Normalise (Effect / Normalise - I normally choose -0.1dB)
• Once the file is ready, choose:
  • File / Export
  • Format: "Other Uncompressed Files"
  • Options
  • Header: "RAW (header-less)"
  • Encoding: "Signed 16-bit PCM"
  • The resulting file will have a .raw suffix. You can't double click to open it again in Audacity, you have to use File / Import / Import Raw Data

Backlog

• Load normal Wav files
• Automatically handle different bit depths / sample rates
• Load compressed mp3/flac files